Video encoding method, video encoding apparatus, video decoding method, video decoding apparatus, and video encoding/decoding apparatus

ABSTRACT

Various embodiments for calculating a motion vector predictor for a current block are provided. A fixed number of motion vector predictor candidates is obtained, with the fixed number being at least two. Each of the motion vector predictor candidates is a candidate for the motion vector predictor. An index for identifying the motion vector predictor from among the fixed number of the motion vector predictor candidates is coded according to the fixed number and added to a bitstream. The motion vector predictor to be used for coding the current block is selected from among the fixed number of the motion vector predictor candidates based on the index. The fixed number of the motion vector predictor candidates includes a plurality of candidates each having a motion vector of value 0, and at least one of one or more first candidates and one or more new candidates.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.13/565,384, filed Aug. 2, 2012, which claims the benefit of U.S.Provisional Patent Application No. 61/514,643, filed on Aug. 3, 2011.The entire disclosure of each of the above-identified applications,including the specification, drawings and claims, is incorporated hereinby reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to moving picture coding methods, movingpicture decoding methods, and the like.

BACKGROUND ART

In moving picture coding processing, in general, the amount ofinformation is reduced by utilizing redundancy in the spatial directionand the temporal direction which moving pictures have. Here, in general,transform to a frequency domain is used as a method utilizing redundancyin the spatial direction. Further, inter-picture prediction(hereinafter, referred to as “inter prediction”) coding processing isused as a method utilizing redundancy in the temporal direction. Ininter prediction coding processing, when a picture is coded, a codedpicture that appears before or after a current picture to be coded inthe display time order is used as a reference picture. A motion vectoris derived by performing motion detection on the current picturerelative to the reference picture. Then, redundancy in the temporaldirection is eliminated by calculating a difference between image dataof the current picture and predicted image data obtained by performingmotion compensation based on the derived motion vector (for example, seeNon Patent Literature (NPL) 1). Here, in motion detection, a differencevalue between a current block in a current picture to be coded and ablock in a reference picture is calculated, and a block in the referencepicture with which the smallest difference value is obtained isdetermined as a reference block. Then, a motion vector is detected usingthe current block and the reference block.

CITATION LIST Non Patent Literature

-   [NPL 1] ITU-T Recommendation H.264, “Advanced video coding for    generic audiovisual services”, March, 2010-   [NPL 2] JCT-VC, “WD3: Working Draft 3 of High-Efficiency Video    Coding”, JCTVC-E603, March 2011

SUMMARY Technical Problem

However, there is a demand for the above conventional technique toachieve an improvement in error resistance in coding and decoding amoving picture using inter prediction.

In view of this, an object of the present disclosure is to provide amoving picture coding method and a moving picture decoding method whichimproves error resistance in coding and decoding a moving picture usinginter prediction.

Solution to Problem

A moving picture coding method according to an aspect of the presentdiscloser is a moving picture coding method for calculating a motionvector predictor to be used when coding a motion vector of a currentblock, and coding the current block to generate a bitstream, the methodincluding: obtaining motion vector predictor candidates a fixed numberof which is two or more and each of which is a candidate for the motionvector predictor; selecting the motion vector, predictor to be used forcoding the motion vector of the current block, from among the motionvector predictor candidates the fixed number of which is two or more;and coding an index for identifying the selected motion vector predictoraccording to the fixed number of two or more, and adding the coded indexto the bitstream, wherein the motion vector predictor candidates thefixed number of which is two or more include one or more candidates eachhaving a predetermined fixed value.

Advantageous Effects

According to an aspect of the present discloser, it is possible toimprove error resistance in coding and decoding a moving picture usinginter prediction.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present invention.

FIG. 1A is a diagram for describing an example of a reference picturelist for a B-picture.

FIG. 1B shows an example of a reference picture list for a predictiondirection 0 for a B-picture.

FIG. 1C shows an example of a reference picture list for a predictiondirection 1 for a B-picture.

FIG. 2 is a diagram for describing motion vectors in a temporal motionvector prediction mode.

FIG. 3 shows examples of motion vectors of adjacent blocks used in amotion vector predictor designating mode.

FIG. 4 is a diagram in (a) and (b) for describing an example of a motionvector predictor candidate list for the prediction direction 0.

FIG. 5 is a diagram in (a) and (b) for describing an example of a motionvector predictor candidate list for the prediction direction 1.

FIG. 6 shows examples of assignment of bit strings to motion vectorpredictor indices.

FIG. 7 is a flowchart showing an example of coding processing performedwhen the motion vector predictor designating mode is used.

FIG. 8A shows an example of calculation of a motion vector predictor.

FIG. 8B shows an example of calculation of a motion vector predictor.

FIG. 9 is a block diagram showing an example of a configuration of amoving picture coding apparatus which codes a moving picture using themotion vector predictor designating mode.

FIG. 10 is a flowchart showing an example of decoding processingperformed when the motion vector predictor designating mode is used.

FIG. 11 is a block diagram showing an example of a configuration of amoving picture decoding apparatus which decodes a moving picture codedusing the motion vector predictor designating mode.

FIG. 12 shows syntax used when a motion vector predictor index is addedto a bitstream.

FIG. 13 is a block diagram showing a configuration of a moving picturecoding apparatus according to Embodiment 1.

FIG. 14 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 1.

FIG. 15A shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 0 in Embodiment 1.

FIG. 15B shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 0 in a modification ofembodiments.

FIG. 15C shows an example in (a)-(c) of a motion vector predictorcandidate list for the prediction direction 0 in the modification of theembodiments.

FIG. 16A shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 1 in Embodiment 1.

FIG. 16B shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 1 in the modification of theembodiments.

FIG. 16C shows an example in (a)-(c) of a motion vector predictorcandidate list for the prediction direction 1 in the modification of theembodiments.

FIG. 17A is a flowchart showing processing for calculating a motionvector predictor candidate and a motion vector predictor candidate listsize in Embodiment 1.

FIG. 17B is a flowchart showing processing for calculating a motionvector predictor candidate in the modification of the embodiments.

FIG. 17C is a flowchart showing processing for calculating a motionvector predictor candidate in the modification of the embodiments.

FIG. 18 is a flowchart showing processing for updating the number ofavailable predictor candidates in Embodiment 1.

FIG. 19A is a flowchart showing processing for adding a new candidate inEmbodiment 1.

FIG. 19B is a flowchart showing processing for adding a new candidate inthe modification of the embodiments.

FIG. 20 is a flowchart showing processing regarding selection of amotion vector predictor candidate in Embodiment 1.

FIG. 21 is a block diagram showing a configuration of a moving picturedecoding apparatus according to Embodiment 2.

FIG. 22 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 2.

FIG. 23 is a flowchart showing processing for calculating the number ofavailable predictor candidates in Embodiment 2.

FIG. 24 is a flowchart showing processing for calculating a motionvector predictor candidate in Embodiment 2.

FIG. 25 shows an example of syntax used when a motion vector predictorindex is added to a bitstream.

FIG. 26 shows an example of syntax used when a motion vector, predictorcandidate list size is fixed to the maximum value of the number ofmotion vector predictor candidates.

FIG. 27 is a flowchart showing processing for adding a second candidatein the modification of the embodiments.

FIG. 28 shows an overall configuration of a content providing system forimplementing content distribution services.

FIG. 29 shows an overall configuration of a digital broadcasting system.

FIG. 30 shows a block diagram illustrating an example of a configurationof a television.

FIG. 31 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk.

FIG. 32 shows an example of a configuration of a recording medium thatis an optical disk.

FIG. 33A shows an example of a cellular phone.

FIG. 33B is a block diagram showing an example of a configuration of acellular phone.

FIG. 34 illustrates a structure of multiplexed data.

FIG. 35 schematically shows how each stream is multiplexed inmultiplexed data.

FIG. 36 shows how a video stream is stored in a stream of PES packets inmore detail.

FIG. 37 shows a structure of TS packets and source packets in themultiplexed data.

FIG. 38 shows a data structure of a PMT.

FIG. 39 shows an internal structure of multiplexed data information.

FIG. 40 shows an internal structure of stream attribute information.

FIG. 41 shows steps for identifying video data.

FIG. 42 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of embodiments.

FIG. 43 shows a configuration for switching between driving frequencies.

FIG. 44 shows steps for identifying video data and switching betweendriving frequencies.

FIG. 45 shows an example of a look-up table in which video datastandards are associated with driving frequencies.

FIG. 46A is a diagram showing an example of a configuration for sharinga module of a signal processing unit.

FIG. 46B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS

(Underlying Knowledge Forming Basis of the Present Disclosure)

In the moving picture coding scheme referred to as H.264 which hasalready been standardized, three picture types, namely, I-picture,P-picture, and B-picture are used to compress the amount of information.

An I-picture is not coded by inter prediction coding processing.Specifically, an I-picture is coded by intra-picture prediction(hereinafter, referred to as intra prediction) coding processing. AP-picture is coded by inter prediction coding by referring to onealready coded picture that appears before or after a current picture tobe coded in the display time order. A B-picture is coded by interprediction coding by referring to two already coded pictures that appearbefore or after the current picture in the display time order.

In inter prediction coding, a reference picture list for identifying areference picture is generated. A reference list is a list in whichreference picture indices are assigned to coded reference pictures to bereferred to in inter prediction. For example, since B-pictures can becoded by referring to two pictures, two reference lists (L0, L1) aregenerated.

FIG. 1A is a diagram for describing an example of a reference picturelist for a B-picture. FIG. 1B shows an example of a reference picturelist 0 (L0) for the prediction direction 0 in bidirectional prediction.Here, in the reference picture list 0, value 0 of the reference pictureindex 0 is assigned to reference picture 0 at display order 2. Further,value 1 of the reference picture index 0 is assigned to referencepicture 1 at display order 1. Further, value 2 of the reference pictureindex 0 is assigned to reference picture 2 at display order 0.Specifically, reference picture indices having smaller values areassigned to reference pictures in order of temporal proximity to acurrent picture to be coded in display order.

FIG. 1C shows an example of the reference picture list 1 (L1) for theprediction direction 1 in bidirectional prediction. Here, in thereference picture list 1, value 0 of the reference picture index 1 isassigned to reference picture 1 at display order 1. Further, value 1 ofthe reference picture index 1 is assigned to reference picture 0 atdisplay order 2. Further, value 2 of the reference picture index 2 isassigned to reference picture 2 at display order 0.

In this manner, it is possible to assign reference picture indiceshaving different values for the prediction directions to a referencepicture (reference pictures 0 and 1 in FIG. 1A), and reference pictureindices having the same value for the prediction directions to areference picture (reference picture 2 in FIG. 1A).

Further, in the moving picture coding scheme referred to as H.264 (NPL1), a motion vector detection mode is used as an inter prediction codingmode for blocks to be coded in a B-picture. In the motion vectordetection mode, a difference value between predicted image data andimage data of a current block to be coded, and a motion vector used forgenerating the predicted image data are coded. Further, in the motionvector detection mode, it is possible to select bidirectional predictionor unidirectional prediction, as the prediction direction. Inbidirectional prediction, a predicted image is generated by referring totwo already coded pictures which appear before or after a currentpicture to be coded. In unidirectional prediction, a predicted image isgenerated by referring to one already coded picture which appears beforeor after a current picture to be coded.

Further, in the moving picture coding scheme referred to as H.264, acoding mode referred to as a temporal motion vector prediction mode canbe selected when a motion vector is derived in coding a B-picture. Aninter prediction coding method in the temporal motion vector predictionmode is described using FIG. 2.

FIG. 2 is a diagram for describing motion vectors in the temporal motionvector prediction mode. Specifically, FIG. 2 shows the case where blocka in picture B2 is to be coded in the temporal motion vector predictionmode.

Here, motion vector vb is utilized which is used when block b(hereinafter, referred to as “co-located block”) at the same position inpicture P3 as that of block a is coded, picture P3 being a referencepicture which appears after picture B2. Motion vector vb is a motionvector used when block b is coded by referring to picture P1.

Two reference blocks for block a are obtained from picture P1 which is aforward reference picture and picture P3 which is a backward referencepicture, using motion vectors parallel to motion vector vb. Then, blocka is coded by performing bidirectional prediction based on the twoobtained reference blocks. Specifically, motion vectors used when blocka is coded are motion vector vat with respect to picture P1 and motionvector vat with respect to picture P3.

In addition, a motion vector predictor designating mode is considered tobe used (NPL 2) as a method for coding motion vectors of blocks to becoded in, a B-picture or a P-picture. In the motion vector predictordesignating mode, motion vector predictor candidates are generated basedon motion vectors used when coding blocks adjacent to a current block tobe coded. Then, a motion vector predictor is selected from among themotion vector predictor candidates, and a motion vector of the currentblock is coded. At this time, an index of the selected motion vectorpredictor and the like are added to a bitstream. Consequently, the samemotion vector predictor as the motion vector predictor used for codingcan be selected also when decoding is performed. A specific example isdescribed with reference to FIG. 3.

FIG. 3 shows examples of motion vectors of adjacent blocks which areused in the motion vector predictor designating mode. In FIG. 3,adjacent block A is a coded block adjacent to and located at the left ofa current block to be coded. Adjacent block B is a coded block adjacentto and located on the current block. Adjacent block C is a coded blockadjacent to and located at the upper right of the current block.Adjacent block D is a coded block adjacent to and located at the bottomleft of the current block.

In FIG. 3, the current block is a block which is coded by bidirectionalprediction, and has, as a result of motion detection or the like, motionvector MvL0 in the prediction direction 0 as a motion vector relative toa reference picture indicated by reference picture index RefL0 for theprediction direction 0, and motion vector MvL1 in the predictiondirection 1 as a motion vector relative to a reference picture indicatedby reference picture index RefL1 for the prediction direction 1. Here,MvL0 is a motion vector for which a reference picture identified usingthe reference picture list 0 (L0) is referred to. Further, MvL1 is amotion vector for which a reference picture identified using thereference picture list 1 (L1) is referred to.

Adjacent block A is a block coded by unidirectional prediction in theprediction direction 0. Adjacent block A has motion vector MvL0_A in theprediction direction 0 as a motion vector relative to a referencepicture indicated by reference picture index RefL0_A for the predictiondirection 0. Further, adjacent block B is a block coded byunidirectional prediction in the prediction direction 1. Adjacent blockB has motion vector MvL1_B in the prediction direction 1 as a motionvector relative to a reference picture indicated by reference pictureindex RefL1_B for the prediction direction 1. Adjacent block C is ablock coded by intra prediction. Further, adjacent block D is a blockcoded by unidirectional prediction in the prediction direction 0.Adjacent block D has motion vector MvL0_D in the prediction direction 0as a motion vector relative to a reference picture indicated byreference picture-index RefL0_D in the prediction direction 0.

In such a case, as a motion vector predictor of a current block to becoded, for example, a motion vector predictor with which a motion vectorof the current block can be most efficiently coded is selected fromamong motion vector predictor candidates generated from motion vectorsof adjacent blocks A, B, C and D and a motion vector in the temporalmotion vector prediction mode obtained using a co-located block. Then, amotion vector predictor index indicating the selected motion vectorpredictor is added to a bitstream. For example, if motion vector MvL0_Ain the prediction direction 0 of adjacent block A is selected as amotion vector predictor when motion vector MvL0 in the predictiondirection 0 of a current block is to be coded, only value “0” of themotion vector predictor index which indicates that the motion vectorpredictor candidate generated from adjacent block A is used as shown inFIG. 4 is added to a bitstream. Accordingly, the amount of informationon motion vector MvL0 in the prediction direction 0 of the current blockcan be reduced.

Here, FIG. 4 shows an example of a motion vector predictor candidatelist for the prediction direction 0. Further, as shown in FIG. 4, in themotion vector predictor designating mode, a candidate with which amotion vector predictor cannot be generated (hereinafter, referred to as“non-available predictor candidate”), and a candidate whose value is thesame as the value of another motion vector predictor candidate(hereinafter, “redundant candidate”) are deleted from motion vectorpredictor candidates. Consequently, the code amount assigned to motionvector predictor indices is reduced by decreasing the number of motionvector predictor candidates. Here, generation of a motion vectorpredictor being impossible means that an adjacent block is (1) a blockcoded by intra prediction, (2) a block outside a boundary of a slice ora picture which includes a current, block to be coded, or (3) a blockwhich is not coded yet, for instance.

In the example in FIG. 4, adjacent block C is coded by intra prediction.Accordingly, a predictor candidate indicated by value “3” of the motionvector predictor index is a non-available predictor candidate, and thusis deleted from the motion vector predictor candidate list. Further, amotion vector predictor in the prediction direction 0 generated fromadjacent block D has the same value as the value of a motion vectorpredictor in the prediction direction 0 generated from adjacent block A,and thus a predictor candidate indicated by value “4” of the motionvector predictor index is deleted from the motion vector predictorcandidate list. As a result, the number of motion vector predictorcandidates in the prediction direction 0 is eventually reduced to 3, andthe motion vector predictor candidate list size for the predictiondirection 0 is set to 3.

FIG. 5 shows an example of a motion vector predictor candidate list forthe prediction direction 1. In the example shown in FIG. 5, the numberof motion vector predictor candidates in the prediction direction 1 iseventually reduced to 2 by deleting a non-available predictor candidateand redundant candidates, and the motion vector predictor candidate listsize for the prediction direction 1 is set to 2.

As shown in FIG. 6, bit strings are assigned to motion vector predictorindices according to the motion vector predictor candidate list size,and are variable-length coded. Further, if the motion vector predictorcandidate list size is 1, a motion vector predictor index is not addedto a bitstream, and a decoding apparatus is caused to estimate that theindex is value 0. In this way, in the motion vector predictordesignating mode, bit strings assigned to motion vector predictorindices are changed according to the motion vector predictor candidatelist size, thereby reducing the code amount.

FIG. 7 is a flowchart showing an example of coding processing in thecase of using the motion vector predictor designating mode.

In step S1001, motion vector predictor candidates in a predictiondirection X are calculated from adjacent blocks and a co-located block(hereafter, referred to as “prediction block candidates”). Here, X isone of the values “0” and “1”, where 0 represents the predictiondirection 0 and 1 represents the prediction direction 1. Motion vectorpredictor candidate sMvLX in the prediction direction X is calculated inaccordance with the following expression, using motion vector MvLX_N andreference picture index RefLX_N of a prediction block candidate andreference picture index RefLX of a current block to be coded.sMvLX=MvLX_N×(POC(RefLX)−curPOC)/(POC(RefLX_N)−curPOC)  (Expression 1)

Here, POC(RefLX) indicates when in the order a reference pictureindicated by reference picture index RefLX is displayed, POC(RefLX_N)indicates when in the order a reference picture indicated by referencepicture index RefLX_N is displayed, and curPOC indicates when in theorder a current picture to be coded is displayed. It should be notedthat if a prediction block candidate does not have motion vector MvLX_Nin the prediction direction X, motion vector predictor sMvLX iscalculated in accordance with Expression 2, using motion vectorMvL(1−X)_N in the prediction direction (1−X) and reference picture indexRefL(1−X)_N.sMvLX=MvL(1−X)_N×(POC(RefLX)−curPOC)/(POC(RefL(1−X)_N)−curPOC)  (Expression2)

FIGS. 8A and 8B show examples of calculating motion vector predictorsusing Expressions 1 and 2. It should be noted that as shown byExpressions 1 and 2, if the values of POC(RefLX) and POC(RefLX_N) arethe same, namely, the same picture is referred to, scaling can beskipped.

In step S1002, a redundant candidate and a non-available predictorcandidate are deleted from motion vector predictor candidates in theprediction direction X.

In step S1003, the motion vector predictor candidate list size is set tothe number of motion vector predictor candidates after the deletingprocessing.

In step S1004, a motion vector predictor index to be used for coding amotion vector in the prediction direction X of a current block isdetermined.

In step S1005, the determined motion vector predictor index isvariable-length coded using a bit string determined according to themotion vector predictor candidate list size.

FIG. 9 is a block diagram showing an example of a configuration of amoving picture coding apparatus 1000 which codes a moving picture usingthe motion vector predictor designating mode.

As shown in FIG. 9, the moving picture coding apparatus 1000 includes asubtraction unit 1001, an orthogonal transform unit 1002, a quantizationunit 1003, an inverse quantization unit 1004, an inverse orthogonaltransform unit 1005, an addition unit 1006, a block memory 1007, a framememory 1008, an intra prediction unit 1009, an inter prediction unit1010, an inter prediction control unit 1011, a picture typedetermination unit 1012, a switch 1013, a motion vector predictorcandidate calculation unit 1014, a colPic memory 1015, and a variablelength coding unit 1016.

In FIG. 9, the motion vector predictor candidate calculation unit 1014calculates motion vector predictor candidates. Then, the motion vectorpredictor candidate calculation unit 1014 transmits the number ofcalculated motion vector predictor candidates to the variable lengthcoding unit 1016. The variable length coding unit 1016 sets the motionvector predictor candidate list size which is a coding parameter to thenumber of motion vector predictor candidates. Then, the variable lengthcoding unit 1016 variable-length codes motion vector predictor indicesused for coding by assigning thereto bit strings according to the motionvector predictor candidate list size.

FIG. 10 is a flowchart showing an example of decoding processing in thecase of using the motion vector predictor designating mode.

In step S2001, motion vector predictor candidates in the predictiondirection X are calculated from adjacent blocks and a co-located block(prediction block candidates). In step S2002, a redundant candidate anda non-available predictor candidate are deleted from the motion vectorpredictor candidates. In step S2003, the motion vector predictorcandidate list size is set to the number of motion vector predictorcandidates after the deleting processing. In step S2004, a motion vectorpredictor index to be used for decoding a current block is decoded froma bitstream using the motion vector predictor candidate list size. Instep S2005, a motion vector is calculated by adding a motion vectordifference to a motion vector predictor candidate indicated by thedecoded motion vector predictor index, and a predicted image isgenerated using the calculated motion vector, thereby performingdecoding processing.

FIG. 11 is a block diagram showing an example of a configuration of amoving picture decoding apparatus which decodes a moving picture codedusing the motion vector predictor designating mode.

As shown in FIG. 11, a moving picture decoding apparatus 2000 includes avariable length decoding unit 2001, an inverse quantization unit 2002,an inverse orthogonal transform unit 2003, an addition unit 2004, ablock memory 2005, a frame memory 2006, an intra prediction unit 2007,an inter prediction unit 2008, an inter prediction control unit 2009, aswitch 2010, a motion vector predictor candidate calculation unit 2011,and a colPic memory 2012.

In FIG. 11, the motion vector predictor candidate calculation unit 2011calculates motion vector predictor candidates. Then, the motion vectorpredictor candidate calculation unit 2011 transmits the number ofcalculated motion vector predictor candidates to the variable lengthdecoding unit 2001. The variable length decoding unit 2001 sets themotion vector predictor candidate list size which is a decodingparameter to the number of motion vector predictor candidates. Then, thevariable length decoding unit 2001 decodes a motion vector predictorindex included in a bitstream using the motion vector predictorcandidate list size.

FIG. 12 shows syntax used when a motion vector predictor index is addedto a bitstream. In FIG. 12, inter_pred_flag indicates a predictiondirection flag for inter prediction, mvp_idx indicates a motion vectorpredictor index, and NumMVPCand indicates the motion vector predictorcandidate list size. NumMVPCand is set to the number of motion vectorpredictor candidates after deleting a non-available predictor candidateand a redundant candidate from the motion vector predictor candidates.

As described above, a moving picture is coded or decoded using themotion vector predictor designating mode. However, in the above motionvector predictor designating mode, the motion vector predictor candidatelist size to be used when a motion vector predictor index is coded ordecoded is set to the number of motion vector predictor candidates. Thisnumber of motion vector predictor candidates is obtained after deletinga non-available predictor candidate or a redundant candidate usingreference picture information including information of a co-locatedblock and the like. Thus, if, for instance, there is a difference in thenumber of motion vector predictor candidates between a moving picturecoding apparatus and a moving picture decoding apparatus, different bitstrings are assigned to motion vector predictor indices in the movingpicture coding apparatus and the moving picture decoding apparatus. As aresult, the moving picture decoding apparatus may not be able to decodea bitstream appropriately.

For example, if information of a reference picture which has beenreferenced as a co-located block is lost due to a packet loss or thelike which has occurred on a transmission channel or the like, a motionvector or a reference picture index of the co-located block will belost. Thus, information on a motion vector predictor candidate to begenerated from the co-located block cannot be obtained. In such a case,a non-available predictor candidate and a redundant candidate cannot beappropriately deleted from motion vector predictor candidates at thetime of decoding. As a result, the moving picture decoding apparatuswill not be able to appropriately obtain the motion vector predictorcandidate list size, and will not be able to successfully decode amotion vector predictor index.

It should be noted that it is possible to fix the motion vectorpredictor candidate list size to address the above problem. If themotion vector predictor candidate list size is fixed, it is notnecessary to obtain the motion vector predictor candidate list size.

However, if the motion vector predictor candidate list size is fixed,when the sum total of one or more candidates each derived from a blockspatially adjacent (each of which is a motion vector predictor candidateother than a redundant candidate and a non-available predictorcandidate) and one or more candidates (first candidates) each derivedfrom a block temporally adjacent (co-located block) is smaller than themotion vector predictor candidate list size, the motion vector predictorcandidate lists will include a null element. In this case, if an imagedecoding apparatus refers to the null element due to the erroroccurrence or the like, unexpected operation may be executed, which is aproblem.

In view of this, an image coding method according to an aspect of thepresent disclosure is a moving picture coding method for calculating amotion vector predictor to be used when coding a motion vector of acurrent block, and coding the current block to generate a bitstream, themethod including: obtaining motion vector predictor candidates a fixednumber of which is two or more and each of which is a candidate for themotion vector predictor; selecting the motion vector predictor to beused for coding the motion vector of the current block, from among themotion vector predictor candidates the fixed number of which is two ormore; and coding an index for identifying the selected motion vectorpredictor according to the fixed number of two or more, and adding thecoded index to the bitstream, wherein the motion vector predictorcandidates the fixed number of which is two or more include one or morecandidates each having a predetermined fixed value.

For example, the motion vector predictor candidates the fixed number ofwhich is two or more may further include at least one of one or morefirst candidates and one or more new candidates, the one or more firstcandidates may be candidates each derived based on a motion vector usedfor coding an adjacent block spatially or temporally adjacent to thecurrent block, and the one or more new candidates may be candidates eachderived based on a motion vector used for coding a block different fromthe adjacent block, or each having a predetermined fixed vector as amotion vector.

For example, the obtaining of the motion vector predictor candidates mayinclude: performing first derivation processing of deriving the one ormore first candidates, and setting, if the one or more first candidatesare derived, each of the derived one or more first candidates as one ofthe motion vector predictor candidates the fixed number of which is twoor more; performing second derivation processing of deriving the one ormore new candidates if a total number of the one or more firstcandidates is smaller than the fixed number of two or more, and setting,if the one or more new candidates are derived, each of the derived oneor more new candidates as one of the motion vector predictor candidatesthe fixed number of which is two or more; and setting, if a sum of thetotal number of one or more first candidates and a total number of theone or more new candidates is smaller than the fixed number of two ormore, at least one of the one or more candidates each having thepredetermined fixed value as one of the motion vector predictorcandidates the fixed number of which is two or more, to make a sum ofthe total number of one or more first candidates, a total number of theone or more candidates each having the predetermined fixed value, andthe total number of new candidates equal to the fixed number of two ormore.

For example, in the second derivation processing, one or more candidatesmay be selected in accordance with a predetermined priority order fromamong a plurality of different candidates previously prepared, to derivethe one or more new candidates.

For example, the obtaining of the motion vector predictor candidates mayinclude: setting the candidate having the predetermined fixed value aseach of all the motion vector predictor candidates the fixed number ofwhich is two or more, to initialize the motion vector predictorcandidates the fixed number of which is two or more; performing firstderivation processing of deriving the one or more first candidates, andupdating the motion vector predictor candidates the fixed number ofwhich is two or more if the one or more first candidates are derived, tocause the motion vector predictor candidates to include the derived oneor more first candidates; and performing second derivation processing ofderiving the one or more new candidates if a total number of the one ormore first candidates is smaller than the fixed number of two or more,and updating the motion vector predictor candidates the fixed number ofwhich is two or more if the one or more new candidates are derived, tocause the motion vector predictor candidates to include the derived oneor more new candidates.

In view of this, an image decoding method according to an aspect of thepresent disclosure is a moving picture decoding method for calculating amotion vector predictor to be used when decoding a motion vector of acurrent block included in a bitstream, and decoding the current block,the method including: obtaining motion vector predictor candidates afixed number of which is two or more and each of which is a candidatefor the motion vector predictor; decoding, according to the fixed numberof two or more, an index for identifying the motion vector predictorcandidate from among the motion vector predictor candidates the fixednumber of which is two or more, the index being coded and added to thebitstream; and selecting, based on the decoded index, the motion vectorpredictor to be used for decoding the current block from among themotion vector predictor candidates the fixed number of which is two ormore, wherein the motion vector predictor candidates the fixed number ofwhich is two or more include one or more candidates each having apredetermined fixed value.

For example, the motion vector predictor candidates the fixed number ofwhich is two or more may further include at least one of one or morefirst candidates and one or more new candidates, the one or more firstcandidates may be candidates each derived based on a motion vector usedfor coding an adjacent block spatially or temporally adjacent to thecurrent block, and the one or more new candidates may be candidates eachderived based on a motion vector used for coding a block different fromthe adjacent block, or each having a predetermined fixed vector as amotion vector.

For example, the obtaining of the motion vector predictor candidates mayinclude: performing first derivation processing of deriving the one ormore first candidates, and setting, if the one or more first candidatesare derived, each of the derived one or more first candidates as one ofthe motion vector predictor candidates the fixed number of which is twoor more; performing second derivation processing of deriving the one ormore new candidates if a total number of the one or more firstcandidates is smaller than the fixed number of two or more, and setting,if the one or more new candidates are derived, each of the derived oneor more new candidates as one of the motion vector predictor candidatesthe fixed number of which is two or more; and setting, if a sum of thetotal number of one or more first candidates and a total number of theone or more new candidates is smaller than the fixed number of two ormore, at least one of the one or more candidates each having thepredetermined fixed value as one of the motion vector predictorcandidates the fixed number of which is two or more, to make a sum ofthe total number of one or more first candidates, a total number of theone or more candidates each having the predetermined fixed value, andthe total number of one or more new candidates equal to the fixed numberof two or more.

For example, in the second derivation processing, one or more candidatesmay be selected in accordance with a predetermined priority order fromamong a plurality of different candidates previously prepared, to derivethe one or more new candidates.

For example, the obtaining of the motion vector predictor candidates mayinclude: setting the candidate having the predetermined fixed value aseach of all the motion vector predictor candidates the fixed number ofwhich is two or more, to initialize the motion vector predictorcandidates the fixed number of which is two or more performing firstderivation processing of deriving the one or more first candidates, andupdating the motion vector predictor candidates the fixed number ofwhich is two or more if the one or more first candidates are derived, tocause the motion vector predictor candidates to include the derived oneor more first candidates; and performing second derivation processing ofderiving the one or more new candidates if a total number of the one ormore first candidates is smaller than the fixed number of two or more,and updating the motion vector predictor candidates the fixed number ofwhich is two or more if the one or more new candidates are derived, tocause the motion vector predictor candidates to include the derived oneor more new candidates.

In view of this, an image coding apparatus according to an aspect of thepresent disclosure is a moving picture coding apparatus for calculatinga motion vector predictor to be used when coding a motion vector of acurrent block, and coding the current block to generate a bitstream, theapparatus including: a motion vector predictor candidate obtaining unitconfigured to obtain motion vector predictor candidates a fixed numberof which is two or more and each of which is a candidate for the motionvector predictor; a selection unit configured to select the motionvector predictor to be used for coding the motion vector of the currentblock, from among the motion vector predictor candidates the fixednumber of which is two or more; and a coding unit configured to code anindex for identifying the selected motion vector predictor according tothe fixed number of two or more, and adding the coded index to thebitstream, wherein the motion vector predictor candidates the fixednumber of which is two or more include one or more candidates eachhaving a predetermined fixed value.

In view of this, an image decoding apparatus according to an aspect ofthe present disclosure is a moving picture decoding apparatus forcalculating a motion vector predictor to be used when decoding a motionvector of a current block included in a bitstream, and decoding thecurrent block, the apparatus including: a motion vector predictorcandidate obtaining unit configured to obtain motion vector predictorcandidates a fixed number of which is two or more and each of which is acandidate for the motion vector predictor; a decoding unit configured todecode, according to the fixed number of two or more, an index foridentifying the motion vector predictor candidate from among the motionvector predictor candidates the fixed number of which is two or more,the index being coded and added to the bitstream; and a selection unitconfigured to select, based on the decoded index, the motion vectorpredictor to be used for decoding the current block from among themotion vector predictor candidates the fixed number of which is two ormore, wherein the motion vector predictor candidates the fixed number ofwhich is two or more include one or more candidates each having apredetermined fixed value.

In view of this, an image coding and decoding apparatus according to anaspect of the present disclosure includes the above-described movingpicture coding apparatus and the above-described moving picture decodingapparatus.

It should be noted that these general and specific aspects may beimplemented using a system, a method, an integrated circuit, a computerprogram, a computer-readable recording medium such as a CD-ROM, or anycombination of systems, methods, integrated circuits, computer programsor recording media.

The following is a specific description of a moving picture codingapparatus and a moving picture decoding apparatus according to an aspectof the present disclosure, with reference to the drawings.

Each of the embodiments described below shows a specific example of thepresent disclosure. The numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements,steps, the processing order of the steps etc. shown in the followingexemplary embodiments are mere examples, and various modifications andrevisions may be made to the present disclosure. Among the structuralelements in the following exemplary embodiments, structural elements notrecited in any one of the independent claims which show the broadestconcept are described as arbitrary structural elements.

Embodiment 1

A moving picture coding apparatus which uses picture coding methodaccording to the present embodiment will be described based on FIGS. 13to 22.

[1-1. Configuration of Moving Picture Coding Apparatus]

First is a description of the configuration of the moving picture codingapparatus based on FIG. 13. FIG. 13 is a block diagram showing aconfiguration of a moving picture coding apparatus 100 according to atEmbodiment 1.

As shown in FIG. 13, the moving picture coding apparatus 100 includes asubtraction unit 101, an orthogonal transform unit 102, a quantizationunit 103, an inverse quantization unit 104, an inverse orthogonaltransform unit 105, an addition unit 106, a block memory 107, a framememory 108, an intra prediction unit 109, an inter prediction unit 110,an inter prediction control unit 111, a picture type determination unit112, a switch 113, a motion vector predictor candidate calculation unit114, a colPic memory 115, and a variable length coding unit 116.

The subtraction unit 101 generates prediction error data by subtracting,for each block, predicted image data from input image data included inan input image sequence. The orthogonal transform unit 102 transformsthe generated prediction error data from an image domain into afrequency domain. The quantization unit 103 performs quantizationprocessing on the prediction error data which has been transformed intothe frequency domain.

The inverse quantization unit 104 performs inverse quantizationprocessing on the prediction error data on which quantization processinghas been performed by the quantization unit 103. The inverse orthogonaltransform unit 105 transforms the prediction error data on which inversequantization processing has been performed, from the frequency domaininto the image domain.

The addition unit 106 generates reconstructed image data by adding, foreach block to be coded, predicted image data and the prediction errordata on which inverse quantization processing has been performed by theinverse orthogonal transform unit 105. The block memory 107 storesreconstructed image data on a block-by-block basis. The frame memory 108stores reconstructed image data on a frame-by-frame basis.

The picture type determination unit 112 determines which of picturetypes, namely, I-picture, B-picture, and P-picture, an input image datais to be coded as. Then, the picture type determination unit 112generates picture type information. The intra prediction unit 109generates intra-predicted image data of a current block to be coded byperforming intra prediction using the reconstructed image data in blockunits stored in the block memory 107. The inter prediction unit 110generates inter-predicted image data of a current block to be coded byperforming inter prediction using the reconstructed image data in frameunits stored in the frame memory 108, and a motion vector derived bymotion detection and the like.

The switch 113 outputs the intra-predicted image data generated by theintra prediction unit 109 to the subtraction unit 101 and the additionunit 106 as predicted image data of the current block, if intraprediction coding is performed on the current block. On the other hand,the switch 113 outputs the inter-predicted image data generated by theinter prediction unit 110 to the subtraction unit 101 and the additionunit 106 as predicted image data of the current block if the interprediction coding is performed on the current block.

The motion vector predictor candidate calculation unit 114 derivesmotion vector predictor candidates in the motion vector predictordesignating mode, using motion vectors of blocks adjacent to the currentblock and the like and colPic information such as information of amotion vector of a co-located block stored in the colPic memory 115.Then, the motion vector predictor candidate calculation unit 114calculates the number of available predictor candidates using the methoddescribed below. Further, the motion vector predictor candidatecalculation unit 114 assigns the values of the motion vector predictorindex to the derived motion vector predictor candidates. Then, themotion vector predictor candidate calculation unit 114 sends the motionvector predictor candidates and the motion vector predictor indices tothe inter prediction control unit 111. The motion vector predictorcandidate calculation unit 114 transmits the number of calculatedavailable predictor candidates to the variable length coding unit 116.

The inter prediction control unit 111 controls the inter prediction unit110 so as to cause the inter prediction unit 110 to perform interprediction coding, using the inter-predicted image generated using amotion vector derived by motion detection. Further, the inter predictioncontrol unit 111 selects, using the method described below, a motionvector predictor candidate most suitable for coding a motion vector usedfor inter prediction coding. Then, the inter prediction control unit 111sends a motion vector predictor index corresponding to the selectedmotion vector predictor candidate, and prediction error information(motion vector difference) to the variable length coding unit 116.Furthermore, the inter prediction control unit 111 transfers colPicinformation including information of a motion vector of the currentblock and the like to the colPic memory 115.

The variable length coding unit 116 performs variable length codingprocessing on prediction error data on which quantization processing hasbeen performed, a prediction direction flag, picture type information,and a motion vector difference, thereby generating a bitstream. Further,the variable length coding unit 116 sets the motion vector predictorcandidate list size to the number of available predictor candidates.Then, the variable length coding unit 116 variable-length codes themotion vector predictor index used for coding a motion vector byassigning, thereto, a bit string according to the motion vectorpredictor candidate list size.

[1-2. Processing Procedure of Moving Picture Coding Method]

Next is a description of processing procedure of the moving picturecoding method executed by the moving picture coding apparatus, based onFIG. 14. FIG. 14 is a flowchart showing processing operation of themoving picture coding apparatus 100 according to Embodiment 1.

In step S101, the inter prediction control unit 111 determines aprediction direction, a reference picture index, and a motion vector ofa current block to be coded by motion detection. Here, in motiondetection, a difference value indicating a difference between a currentblock to be coded in a picture to be coded and a block in a referencepicture is calculated, and a block in the reference picture with whichthe difference value is smallest is determined as a reference block.Then, a motion vector is obtained based on the position of a currentblock to be coded and the position of a reference block position usingthe method for obtaining a motion vector, for instance. Further, theinter prediction control unit 111 performs motion detection on each ofreference pictures in the prediction directions 0 and 1, and determineswhether to select the prediction direction 0, the prediction direction 1or bidirectional prediction using, for example, the following expressionfor an R-D optimization model, or the like.Cost=D+λ×R  (Expression 3)

In Expression 3, D denotes coding distortion. For instance, a sum ofabsolute differences are used for the coding distortion D each of whichis an absolute difference between a pixel value obtained by coding anddecoding a current block using a predicted image generated using acertain motion vector and an original pixel value of the current block.R denotes a generated code amount. For instance, a code amount necessaryto code a motion vector used for generating a predicted image is usedfor the generated code amount R. Further, λ denotes a Lagrangeundetermined multiplier.

In step S102, the motion vector predictor candidate calculation unit 114derives motion vector predictor candidates from blocks adjacent to thecurrent block and a co-located block thereof. Further, the motion vectorpredictor candidate calculation unit 114 calculates the motion vectorpredictor candidate list size according to the method described below.

For example, in the case as shown in FIG. 3, the motion vector predictorcandidate calculation unit 114 selects motion vectors which adjacentblocks A, B, C, and D have, as motion vector predictor candidates of thecurrent block. Furthermore, the motion vector predictor candidatecalculation unit 114 calculates a motion vector, for instance, which iscalculated using a temporal prediction mode from a motion vector of theco-located block, as a motion vector predictor candidate.

The motion vector predictor candidate calculation unit 114 assignsmotion vector predictor indices to the motion vector predictorcandidates in the prediction directions 0 and 1, as shown in (a) in FIG.15A and (a) in FIG. 16A. Then, the motion vector predictor candidatecalculation unit 114 calculates motion vector predictor candidate listsas shown in (b) in FIG. 15A and (b) in FIG. 16A, and the sizes of themotion vector predictor candidate lists by deleting a non-availablepredictor candidate and a redundant candidate and adding a newcandidate, using the method described below.

The smaller a value of a motion vector predictor index is, the shortercode is assigned to the motion vector predictor index. Specifically, ifthe value of a motion vector predictor index is small, the amount ofinformation necessary for the motion vector predictor index is small. Onthe other hand, if the value of a motion vector predictor index islarge, the amount of information necessary for the motion vectorpredictor index is large. Thus, coding efficiency is increased byassigning a motion vector predictor index having a small value to amotion vector predictor candidate having a high possibility of becominga motion vector predictor with high precision.

In view of this, the motion vector predictor candidate calculation unit114 may measure, for each motion vector predictor candidate, the numberof times at which the motion vector predictor candidate has beenselected as a motion vector predictor, and assign a motion vectorpredictor index having a small value to a motion vector predictorcandidate whose number of times at which the candidate has been selectedis large, for example. Specifically, it is possible to consideridentifying a motion vector predictor selected in an adjacent block, andin coding a current block, assigning a motion vector predictor indexhaving a small value to the identified motion vector predictorcandidate.

It should be noted that if an adjacent block does not have informationof a motion vector and the like (if the adjacent block is coded by intraprediction, if the adjacent block is located, for instance, outside aboundary of a picture or a slice, if the adjacent block is not codedyet, or the like), the adjacent block cannot be utilized as a motionvector predictor candidate.

In the present embodiment, a candidate that cannot utilized as a motionvector predictor candidate is referred to as a non-available predictorcandidate. A candidate that can be utilized as a motion vector predictorcandidate is referred to as an available predictor candidate. Further,among a plurality of motion, vector predictor candidates, a candidatewhose value is the same as any one of the other motion vector predictorsis referred to as a redundant candidate.

In the case of FIG. 3, adjacent block C is a block coded by intraprediction, and thus is assumed to be a non-available predictorcandidate. Further, motion vector predictor sMvL0_D in the predictiondirection 0 generated from adjacent block D has the same value as thevalue of motion vector predictor MvL0_A in the prediction direction 0generated from adjacent block A, and thus is assumed to be a redundantcandidate.

In step S103, the inter prediction control unit 111 determines a valueof a motion vector predictor index to be used for coding a motion vectorin the prediction direction X by using the method described below.

In step S104, the variable length coding unit 116 variable length-codesmotion vector predictor indices of motion vector predictor candidates tobe used for coding motion vectors in the prediction direction X byassigning thereto bit strings according to the motion vector predictorcandidate list size as shown in FIG. 6.

In the present embodiment, as shown in (a) in FIG. 15A and (a) in FIG.16A, “0” is assigned as a value of a motion vector predictor indexcorresponding to adjacent block A. “1” is assigned as a value of amotion vector predictor index corresponding to adjacent block B. “2” isassigned as a value of a motion vector predictor index corresponding toa co-located block. “3” is assigned as a value of a motion vectorpredictor index corresponding to adjacent block C. “4” is assigned as avalue of a motion vector predictor index corresponding to adjacent blockD.

It should be noted that the way to assign motion vector predictorindices is not necessarily limited to this example. For example, if anew candidate is added using the method described below, the variablelength coding unit 116 may assign a small value to a motion vectorpredictor candidate which is not newly added (and corresponds to a firstcandidate), and a large value to the new candidate. Specifically, thevariable length coding unit 116 may preferentially assign a motionvector predictor index having a small value to a motion vector predictorcandidate which is not newly added. It should be noted that if a secondcandidate is used using a method described below, a value smaller thanthat of the second candidate is assigned to each of the values of motionvector predictor indices of a first candidate and a new candidate. Thisis because the second candidate is a candidate to be assigned to a nullelement of the motion vector predictor candidate lists when the motionvector predictor candidate list size is fixed and when the number offirst candidates and new candidates is smaller than the motion vectorpredictor candidate list size.

Further, motion vector predictor candidates are not necessarily limitedto be at the positions of adjacent blocks A, B, C, and D. For example,an adjacent block located on bottom-left adjacent block D, for instance,may be used to obtain a motion vector predictor candidate. Further, allthe adjacent blocks do not necessarily need to be used to obtain motionvector predictor candidates. For example, only adjacent blocks A and Bmay be used to obtain motion vector predictor candidates. Alternatively,adjacent blocks may be sequentially scanned by using, for instance,adjacent block A if adjacent block D is a non-available predictorcandidate.

Further, in the present embodiment, although the variable length codingunit 116 adds a motion vector predictor index to a bitstream in stepS104 in FIG. 14, a motion vector predictor index does not necessarilyneed to be added to a bitstream. For example, if the motion vectorpredictor candidate list size is 1, the variable length coding unit 116may not add a motion vector predictor index to a bitstream. Accordingly,the amount of information can be reduced by that of the motion vectorpredictor index.

FIG. 17A is a flowchart showing detailed processing of step S102 in FIG.14. Specifically, FIG. 17A shows a method for calculating motion vectorpredictor candidates and the motion vector predictor candidate listsize. The following is a description of FIG. 17A.

In step S111, the motion vector predictor candidate calculation unit 114determines, using the method described below, whether a prediction blockcandidate [N] is an available predictor candidate. Then, the motionvector predictor candidate calculation unit 114 updates the number ofavailable predictor candidates in accordance with the determinationresult.

Here, N is an index value for denoting each prediction block candidate.In the present embodiment, N is one of the values from 0 to 4.Specifically, adjacent block A in FIG. 3 is assigned to a predictionblock candidate [0]. Adjacent block B in FIG. 3 is assigned to aprediction block candidate [1]. A co-located block is assigned to aprediction block candidate [2]. Adjacent block C in FIG. 3 is assignedto a prediction block candidate [3]. Adjacent block D in FIG. 3 isassigned to a prediction block candidate [4].

In step S112, the motion vector predictor candidate calculation unit 114derives a motion vector predictor candidate in the prediction directionX from the prediction block candidate [N] using Expressions 1 and 2above, and adds the derived candidate to a corresponding one of themotion vector predictor candidate lists.

In step S113, the motion vector predictor candidate calculation unit 114searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists, asshown in FIGS. 15A and 16A.

In step S114, the motion vector predictor candidate calculation unit 114adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists by using the method described below. Here,when a new candidate is added, the motion vector predictor candidatecalculation unit 114 may reassign values of motion vector predictorindices so as to preferentially assign a small motion vector predictorindex to a motion vector predictor candidate which is not newly added.Specifically, the motion vector predictor candidate calculation unit 114may reassign values of motion vector predictor indices so as to assign amotion vector predictor index having a large value to the new candidate.In this manner, the amount of coding motion vector predictor indices canbe reduced.

In step S115, the motion vector predictor candidate calculation unit 114sets the motion vector predictor candidate list size to the number ofavailable predictor candidates calculated in step S111. In the examplesof FIGS. 15A and 16A, by using the method described below, “4” iscalculated as the number of available predictor candidates in theprediction direction 0, and the motion vector predictor candidate listsize for the prediction direction 0 is set to “4”. Further, “4” iscalculated as the number of available predictor candidates in theprediction direction 1, and the motion vector predictor candidate listsize for the prediction direction 1 is set to “4”.

It should be noted that a new candidate in step S114 is a candidatenewly added to motion vector predictor candidates using the methoddescribed below, if the number of motion vector predictor candidates hasnot reached the number of available predictor candidates. For example, anew candidate may be a motion vector predictor generated from anadjacent block located on bottom-left adjacent block D in FIG. 3. A newcandidate may be a motion vector predictor generated from blockscorresponding to blocks A, B, C, and D adjacent a co-located block, forexample. Further, a new candidate may be a motion vector predictorcalculated from a total of motion vectors in the entire picture plane ora certain area of a reference picture, for example. In this way, codingefficiency can be improved by the motion vector predictor candidatecalculation unit 114 adding a new motion vector predictor as a newcandidate if the number of motion vector predictor candidates has notreached the number of available predictor candidates.

FIG. 18 is a flowchart showing detailed processing of step S111 in FIG.17A. Specifically, FIG. 18 shows a method for determining whether theprediction block candidate [N] is an available predictor candidate, andupdating the number of available predictor candidates. The following isa description of FIG. 18.

In step S121, the motion vector predictor candidate calculation unit 114determines whether a prediction block candidate [N] is (1)intra-predicted, (2) located outside a boundary of a slice or a picturewhich includes a current block to be coded, or (3) is not coded yet.

If the determination result in step S121 is true here (Yes in stepS121), the motion vector predictor candidate calculation unit 114 setsthe prediction block candidate [N] as a non-available predictorcandidate in step S122. On the other hand, if the determination resultin step S121 is false (No in step S121), the motion vector predictorcandidate calculation unit 114 sets the prediction block candidate [N]as an available predictor candidate in step S123.

In step S124, the motion vector predictor candidate calculation unit 114determines whether the prediction block candidate [N] is an availablepredictor candidate or a co-located block candidate. Here, if thedetermination result in step S124 is true (Yes in step S124), the motionvector predictor candidate calculation unit 114 adds 1 to the number ofavailable predictor candidates, and updates the number of motion vectorpredictor candidates in step S5. On the other hand, if the determinationresult in step S124 is false (No in step S124), the motion vectorpredictor candidate calculation unit 114 does not update the number ofavailable predictor candidates.

As described above, if a prediction block candidate is a co-locatedblock, the motion vector predictor candidate calculation unit 114 adds 1to the number of available predictor candidates, irrespective of whetherthe co-located block is an available predictor candidate or anon-available predictor candidate. Accordingly, even if information of aco-located block is lost due to packet loss or the like, there is nodifference in the number of available predictor candidates between themoving picture coding apparatus and the moving picture decodingapparatus.

The motion vector predictor candidate list size is set to the number ofavailable predictor candidates in step S115 in FIG. 17A. Furthermore, instep S104 in FIG. 14, the motion vector predictor candidate list size isused for variable-length coding motion vector predictor indices.Accordingly, even if reference picture information including informationof a co-located block and the like is lost, the moving picture codingapparatus 100 can generate a bitstream from which a motion vectorpredictor index can be successfully decoded.

FIG. 19A is a flowchart showing detailed processing of step S114 in FIG.17A. Specifically, FIG. 19A shows a method for adding a new candidate.The following is a description of FIG. 19A.

In step S131, the motion vector predictor candidate calculation unit 114determines whether the number of motion vector predictor candidates issmaller than the number of available predictor candidates. Specifically,the motion vector predictor candidate calculation unit 114 determineswhether the number of motion vector predictor candidates has not reachedthe number of available predictor candidates.

Here, if the determination result in step S131 is true (Yes in stepS131), the motion vector predictor candidate calculation unit 114determines in step S132 whether there is a new candidate which can beadded to a corresponding one of the motion vector predictor candidatelists as a motion vector predictor candidate. Here, if the determinationresult in step S132 is true (Yes in step S132), the motion vectorpredictor candidate calculation unit 114 assigns a value of a motionvector predictor index to the new candidate, and adds the new candidateto a corresponding one of the motion vector predictor candidate lists instep S133. Furthermore, in step S134, the motion vector predictorcandidate calculation unit 114 adds 1 to the number of motion vectorpredictor candidates.

On the other hand, if the determination result in step S131 or step S132is false (No in step S131 or S132), new candidate adding processingends. Specifically, if the number of motion vector predictor candidateshas reached the number of available predictor candidates, or if there isno new candidate, new candidate adding processing ends.

FIG. 20 is a flowchart showing detailed processing of step S103 in FIG.14. Specifically, FIG. 20 shows processing regarding selection of amotion vector predictor candidate. The following is a description ofFIG. 20.

In step S141, as initialization, the inter prediction control unit 111sets motion vector predictor candidate index mvp_idx to 0, and sets thesmallest motion vector difference to the maximum value.

In step S142, the inter prediction control unit 111 determines whetherthe value of motion vector predictor candidate index mvp_idx is smallerthan the number of motion vector predictor candidates. Specifically, theinter prediction control unit 111 determines whether motion vectordifferences of all the motion vector predictor candidates have beencalculated.

Here, if there still remains a motion vector predictor candidate forwhich calculation has not been performed (Yes in step S142), the interprediction control unit 111 calculates a motion vector difference bysubtracting a motion vector predictor candidate from a motion vectorobtained as a result of motion detection (motion detection resultantvector) in step S143.

In step S144, the inter prediction control unit 111 determines whetherthe motion vector difference obtained in step S143 has a value smallerthan the smallest motion vector difference.

Here, if the determination result in step S144 is true (Yes in stepS144), the inter prediction control unit 111 updates the smallest motionvector difference and the value of a motion vector predictor index instep S145. On the other hand, if the determination result in step S144is false (No in step S144), the inter prediction control unit 111 doesnot update the smallest motion vector difference and the value of amotion vector predictor index.

In step S146, the inter prediction control unit 111 updates a motionvector predictor candidate index by incrementing by +1, and returningback to step S142, the inter prediction control unit 111 determineswhether a next motion vector predictor candidate is present.

On the other hand, if it is determined in step S142 that a motion vectordifference has been calculated for all the motion vector predictorcandidates (No in step S142), the inter prediction control unit 111fixes, in step S147, the smallest motion vector difference and themotion vector predictor index which are set at last.

In this way, according to the moving picture coding apparatus 100according to the present embodiment, the motion vector predictorcandidate list size to be used when a motion vector predictor index iscoded or decoded can be calculated using a method independent ofreference picture information including information of a co-locatedblock and the like. Accordingly, the moving picture coding apparatus 100can improve error resistance.

More specifically, the moving picture coding apparatus 100 according tothe present embodiment adds 1 to the number of available predictorcandidates if a prediction block candidate is a co-located block,irrespective of whether the co-located block is an available predictorcandidate. Then, the moving picture coding apparatus 100 determines abit string to be assigned to a motion vector predictor index using thenumber of available predictor candidates calculated in this way.Accordingly, the moving picture coding apparatus 100 can generate abitstream from which a motion vector predictor index can be successfullydecoded even if reference picture information including information of aco-located block is lost.

Further, the moving picture coding apparatus 100 according to thepresent embodiment can improve coding efficiency by adding a newcandidate having a new motion vector predictor as a motion vectorpredictor candidate if the number of motion vector predictor candidateshas not reached the number of available predictor candidates.

It should be noted that although in the present embodiment, the movingpicture coding apparatus 100 adds a new candidate having a new motionvector predictor as a motion vector predictor candidate if the number ofmotion vector predictor candidates has not reached the number ofavailable predictor candidates, the present embodiment is not limited tothis. For example, the moving picture coding apparatus 100 may set a newcandidate having a new motion vector predictor as an initial value ofall the motion vector predictor candidates on the motion vectorpredictor candidate lists when the motion vector predictor candidatelists are created. In this case, the moving picture coding apparatus 100will calculate a motion vector predictor candidate, and overwrite thenew candidate which is an initial value when the calculated motionvector predictor candidate is added to a corresponding one of the motionvector predictor candidate lists. Then, the moving picture codingapparatus 100 determines whether the calculated motion vector predictorcandidate is a non-available predictor candidate or a redundantcandidate, before the calculated motion vector predictor candidate isadded to the corresponding motion vector predictor candidate list.Accordingly, if there is a non-available predictor candidate or aredundant candidate, the new candidate which is an initial value remainsin the corresponding motion vector predictor candidate list. It is alsopossible to add a new candidate as a motion vector predictor candidateby using such a method.

In the present embodiment, the moving picture coding apparatus 100determines a bit string to be assigned to a motion vector predictorindex using the number of available predictor candidates calculated byalways adding 1 if a prediction block candidate is a co-located blockirrespective of whether the co-located block is an available predictorcandidate, the present disclosure is not limited to this.

For example, the moving picture coding apparatus 100 may determine a bitstring to be assigned to a motion vector predictor index, using thenumber of available predictor candidates calculated by always adding 1also in the case of a prediction block candidate other than theco-located block in step S124 in FIG. 18. Specifically, the movingpicture coding apparatus 100 may assign a bit string to a motion vectorpredictor index using the motion vector predictor candidate list sizefixed to the maximum value M of the number of motion vector predictorcandidates. In other words, assuming that all prediction blockcandidates are available predictor candidates, the moving picture codingapparatus 100 may fix the motion vector predictor candidate list size tothe maximum value M of the number of motion vector predictor candidates,and code motion vector predictor indices.

For example, in the present embodiment, the maximum value M of thenumber of motion vector predictor candidates is 5 (adjacent block A,adjacent block B, co-located block, adjacent block C, adjacent block D),and thus the moving picture coding apparatus 100 may always set themotion vector predictor candidate list size to 5, and code motion vectorpredictor indices. Further; for example, if the maximum value M of thenumber of motion vector predictor candidates is 4 (adjacent block A,adjacent block B, adjacent block C, adjacent block D), the movingpicture coding apparatus 100 may always set the motion vector predictorcandidate list size to 4, and code motion vector predictor indices.

In this way, the moving picture coding apparatus 100 may determine themotion vector predictor candidate list size according to the maximumvalue M of the number of motion vector predictor candidates.Accordingly, it is possible to generate a bitstream from which thevariable length decoding unit of the moving picture decoding apparatuscan decode a motion vector predictor index in the bitstream withoutreferring to information of adjacent blocks or a co-located block, whichresults in a reduction of the amount of processing to be performed bythe variable length decoding unit.

Furthermore, the maximum value M of the number of motion vectorpredictor candidates may be embedded in a sequence parameter set (SPS),a picture parameter set (PPS), or a slice header, for instance.Accordingly, the maximum value M of the number of motion vectorpredictor candidates can be changed according to a current picture to becoded, thereby reducing the amount of processing and improving codingefficiency.

For example, it can be considered that the maximum value of the numberof motion vector predictor candidates is set to 4 (adjacent block A,adjacent block B, adjacent block C, adjacent block D) in the case of apicture for which a co-located block is not referred to (a B-picture ora P-picture for which an I-picture is referred to), whereas the maximumvalue of the number of motion vector predictor candidates is set to 5(adjacent block A, adjacent block B, co-located block, adjacent block C,adjacent block D) in the case of a picture for which a co-located blockis referred to, and that maximum value is embedded into a sequenceparameter set (SPS), a picture parameter set (PPS), or a slice header,for instance.

Embodiment 2

A moving picture decoding apparatus which uses a moving picture decodingmethod according to the present embodiment is described based on FIGS.21 to 24.

[2-1. Configuration of Moving Picture Decoding Apparatus]

First is a description of the configuration of a moving picture decodingapparatus based on FIG. 21. FIG. 21 is a block diagram showing aconfiguration of a moving picture decoding apparatus 300 according toEmbodiment 3.

As shown in FIG. 21, the moving picture decoding apparatus 300 includesa variable length decoding unit 301, an inverse quantization unit 302,an inverse orthogonal transform unit 303, an addition unit 304, a blockmemory 305, a frame memory 306, an intra prediction unit 307, an interprediction unit 308, an inter prediction control unit 309, a switch 310,a motion vector predictor candidate calculation unit 311, and a colPicmemory 312.

The variable length decoding unit 301 performs variable length decodingprocessing on an input bitstream, and generates picture typeinformation, a prediction direction flag, a quantization coefficient,and a motion vector difference. Further, the variable length decodingunit 301 performs variable length decoding processing on motion vectorpredictor indices using the number of available predictor candidatesdescribed below.

The inverse quantization unit 302 performs inverse quantizationprocessing on the quantization coefficient obtained by variable lengthdecoding processing. The inverse orthogonal transform unit 303transforms an orthogonal transform coefficient obtained by inversequantization processing from a frequency domain into an image domain, togenerate prediction error data. The block memory 305 stores decodedimage data generated by adding prediction error data and predicted imagedata, on a block-by-block basis. The frame memory 306 stores decodedimage data on a frame-by-frame basis.

The intra prediction unit 307 generates predicted image data of acurrent block to be decoded by performing intra prediction using decodedimage data in block units stored in the block memory 305. The interprediction unit 308 generates predicted image data of a current block tobe decoded by performing inter prediction using decoded image data inframe units stored in the frame memory 306.

If intra prediction decoding is performed on the current block, theswitch 310 outputs the intra-predicted image data generated by the intraprediction unit 307 to the addition unit 304 as predicted image data ofthe current block. In contrast, if inter prediction decoding isperformed on the current block, the switch 310 outputs theinter-predicted image data generated by the inter prediction unit 308 tothe addition unit 304 as predicted image data of the current block.

Using, for instance, motion vectors of blocks adjacent to a currentblock to be decoded and colPic information such as information of amotion vector of a co-located block stored in the colPic memory 312, themotion vector predictor candidate calculation unit 311 derives motionvector predictor candidates in the motion vector predictor designatingmode by using the method described below. Further, the motion vectorpredictor candidate calculation unit 311 assigns a value of a motionvector predictor index to each derived motion vector predictorcandidate. Then, the motion vector predictor candidate calculation unit311 sends the motion vector predictor candidates and the motion vectorpredictor indices to the inter prediction control unit 309.

The inter prediction control unit 309 selects, from among the motionvector predictor candidates, a motion vector predictor to be used forinter prediction, based on the decoded motion vector predictor index.Then, the inter prediction control unit 309 calculates a motion vectorof the current block, based on the motion vector predictor and a motionvector difference. Then, the inter prediction control unit 309 causesthe inter prediction unit 308 to generate an inter-predicted image usingthe calculated motion vector. Further, the inter prediction control unit309 transfers colPic information including information of the motionvector of the current block and the like to the colPic memory 312.

Finally, the addition unit 304 generates decoded image data by addingpredicted image data and prediction error data.

[1-2. Processing Procedure of Moving Picture Coding Method]

Next is a description of the processing procedure of the moving picturecoding method executed by the moving picture coding apparatus, based onFIG. 22. FIG. 22 is a flowchart showing processing operation of themoving picture decoding apparatus 300 according to Embodiment 3.

In step S301, the variable length decoding unit 301 decodes a predictiondirection flag and a reference picture index. Then, the value of theprediction direction X is determined according to the decoded predictiondirection flag, and processing of the following steps S302 to S305 isperformed.

In step S302, the motion vector predictor candidate calculation unit 311calculates the number of available predictor candidates using the methoddescribed below. Then, the motion vector predictor candidate calculationunit 311 sets the motion vector predictor candidate list size to thecalculated number of available predictor candidates.

In step S303, the variable length decoding unit 301 variable-lengthdecodes the motion vector predictor index in a bitstream using thecalculated motion vector predictor candidate list size.

In step S304, the motion vector predictor candidate calculation unit 311generates motion vector predictor candidates from blocks adjacent to thecurrent block and a co-located block using the method described below.

In step S305, the inter prediction control unit 309 adds the decodedmotion vector difference to the motion vector predictor candidateindicated by the decoded motion vector predictor index, to calculate amotion vector. Then, the inter prediction control unit 309 causes theinter prediction unit 308 to generate an inter-predicted image using thecalculated motion vector.

It should be noted that if the motion vector predictor candidate listsize calculated in step S302 is “1”, it may be estimated that a motionvector predictor index is 0, without being decoded.

FIG. 23 is a flowchart showing detailed processing of step S302 in FIG.22. Specifically, FIG. 23 shows a method for determining whether aprediction block candidate [N] is an available predictor candidate, andcalculating the number of available predictor candidates. The followingis a description of FIG. 23.

In step S311, the motion vector predictor candidate calculation unit 311determines whether a prediction block candidate [N] is (1) decoded byintra prediction, (2) located outside a boundary of a slice or a picturewhich includes a current block to be decoded, or (3) not decoded yet.

Here, if the determination result in step S311 is true (Yes in stepS311), the motion vector predictor candidate calculation unit 311 setsthe prediction block candidate [N] as a non-available predictorcandidate in step S312. On the other hand, if the determination resultin step S311 is false (No in S311), the motion vector predictorcandidate calculation unit 311 sets the prediction block candidate [N]as an available predictor candidate in step S313.

In step S314, the motion vector predictor candidate calculation unit 311determines whether the prediction block candidate [N] is an availablepredictor candidate or a co-located block candidate. Here, if thedetermination result in step S314 is true (Yes in step S314), the motionvector predictor candidate calculation unit 311 adds 1 to the number ofavailable predictor candidates, and updates the value in step S5. On theother hand, if the determination result in step S314 is false (No instep S314), the motion vector predictor candidate calculation unit 311does not update the number of available predictor candidates.

As described above, if a prediction block candidate is a co-locatedblock, the motion vector predictor candidate calculation unit 311 adds 1to the number of available predictor candidates, irrespective of whetherthe co-located block is an available predictor candidate or anon-available predictor candidate. Accordingly, even if information of aco-located block is lost due to packet loss or the like, there is nodifference in the number of available predictor candidates between themoving picture coding apparatus and the moving picture decodingapparatus.

The motion vector predictor candidate list size is set to the number ofavailable predictor candidates in step S302 in FIG. 22. Furthermore, inS303 in FIG. 22, the motion vector predictor candidate list size is usedfor variable-length decoding motion vector predictor indices.Accordingly, even if reference picture information including informationof a co-located block or the like is lost, the moving picture decodingapparatus 300 can successfully decode motion vector predictor indices.

FIG. 24 is a flowchart showing detailed processing of step S304 in FIG.22. Specifically, FIG. 24 shows a method for calculating motion vectorpredictor candidates. The following is a description of FIG. 24.

In step S321, the motion vector predictor candidate calculation unit 311calculates, from the prediction block candidate [N], a motion vectorpredictor candidate in the prediction direction X using Expressions 1and 2 above, and adds the calculated candidate to a corresponding one ofthe motion vector predictor candidate lists.

In step S322, the motion vector predictor candidate calculation unit 311searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists, asshown in FIGS. 15A and 16A.

In step S323, the motion vector predictor candidate calculation unit 311adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists using the same method as in FIG. 19A.

FIG. 25 shows an example of syntax used when a motion vector predictorindex is added to a bitstream. In FIG. 25, inter_pred_flag indicates aprediction direction flag, and mvp_idx indicates a motion vectorpredictor index. NumMVPCand indicates the motion vector predictorcandidate list size, and the size is set to the number of availablepredictor candidates calculated in the processing flow in FIG. 23 in thepresent embodiment.

As described above, according to the moving picture decoding apparatus300 according to the present embodiment, the motion vector predictorcandidate list size to be used when a motion vector predictor index iscoded or decoded can be calculated by using a method independent ofreference picture information including information of a co-locatedblock and the like. Accordingly, the moving picture decoding apparatus300 can appropriately decode a bitstream having improved errorresistance.

More specifically, the moving picture decoding apparatus 300 accordingto the present embodiment always adds 1 to the number of availablepredictor candidates if a prediction block candidate is a co-locatedblock, irrespective of whether the co-located block is an availablepredictor candidate. Then, the moving picture decoding apparatus 300determines bit strings to be assigned to motion vector predictor indicesusing the number of available predictor candidates calculated in thisway. Accordingly, even if reference picture information includinginformation of a co-located block is lost, the moving picture decodingapparatus 300 can successfully decode a motion vector predictor index.

Further, if the number of motion vector predictor candidates has notreached the number of available predictor candidates, the moving picturedecoding apparatus 300 according to the present embodiment canappropriately decode a bitstream for which coding efficiency has beenimproved by adding a new candidate having a new motion vector predictoras a motion vector predictor candidate.

It should be noted that in the present embodiment, although the movingpicture decoding apparatus 300 adds a new candidate having a new motionvector predictor as a motion vector predictor candidate if the number ofmotion vector predictor candidates has not reached the number ofavailable predictor candidates, the present disclosure is not limited tothis. For example, as in Embodiment 1 described above, when creating themotion vector predictor candidate lists, the moving picture decodingapparatus 300 may seta new candidate having a new motion vectorpredictor as an initial value of all the motion vector predictorcandidates on the motion vector predictor candidate lists.

It should be noted that although the moving picture decoding apparatus300 according to the present embodiment determines bit strings to beassigned to motion vector predictor indices using the number ofavailable predictor candidates calculated by always adding 1 when aprediction block candidate is a co-located block, irrespective ofwhether the co-located block is an available predictor candidate, thepresent disclosure is not limited to this.

For example, the moving picture decoding apparatus 300 may determine bitstrings to be assigned to motion vector predictor indices, using thenumber of available predictor candidates calculated by always adding 1also in the case of a prediction block candidate other than a co-locatedblock in step S314 in FIG. 23. Specifically, the moving picture decodingapparatus 300 may assign a bit string to a motion vector predictorindex, using the motion vector predictor candidate list size fixed tothe maximum value M of the number of motion vector predictor candidates.In other words, assuming that all prediction block candidates areavailable predictor candidates, the moving picture decoding apparatus300 may fix the motion vector predictor candidate list size to themaximum value M of the number of motion vector predictor candidates, anddecode motion vector predictor indices.

For example, in the present embodiment, since the maximum value M of thenumber of motion vector predictor candidates is 5 (adjacent block A,adjacent block B, co-located block, adjacent block C, adjacent block D),the moving picture decoding apparatus 300 may always set the motionvector predictor candidate list size to 5, and decode motion vectorpredictor indices. Furthermore, when the maximum value M of the numberof motion vector predictor candidates is 4 (adjacent block A, adjacentblock B, adjacent block C, adjacent block D) in the case of a picturefor which a co-located block is not referred to (a B-picture or aP-picture for which an I-picture is referred to), the moving picturedecoding apparatus 300 may always set the motion vector predictorcandidate list size to 4, and code motion vector predictor indices.

Accordingly, the variable length decoding unit 301 of the moving picturedecoding apparatus 300 can decode a motion vector predictor index in abitstream, without referring to information of an adjacent block or aco-located block. For example, the amount of processing to be performedby the variable length decoding unit 301 can be reduced by, forinstance, skipping processing of steps S314 and S315 in FIG. 23.

FIG. 26 shows an example of syntax used when the motion vector predictorcandidate list size is fixed to the maximum value M of the number ofmotion vector predictor candidates. If the motion vector predictorcandidate list size is fixed to the maximum value of the number ofmotion vector predictor candidates, NumMVPCand can be deleted from thesyntax as shown in FIG. 26, compared to the case of FIG. 25.

The maximum value M of the number of motion vector predictor candidatesmay be obtained from SPS, PPS, or a slice header. This enables themaximum value M of the number of motion vector predictor candidates tobe changed according to a current picture to be decoded, therebyreducing the amount of processing, and improving coding efficiency.Thus, a bitstream can be decoded properly.

Modification of Embodiments 1 and 2

In Embodiments 1 and 2 described above, when the motion vector predictorcandidate list size is fixed to the maximum value of the number ofmotion vector predictor candidates (corresponding to an example of afixed number of two or more), if the motion vector predictor candidatelists have null elements, a predetermined motion vector predictorcandidate for the improvement in error resistance (second candidate) maybe inserted into each null portion of the motion vector predictorcandidate lists, to improve error resistance.

As the second candidate, a motion vector predictor candidate having amotion vector whose magnitude is (0, 0), for example, may be assigned.The second candidate is a candidate for improving error resistance, andthus even if a plurality of second candidates are to be added, all thesecond candidates may be set to the same value. On the contrary, a newcandidate is a candidate for improving coding efficiency, and thusdifferent candidates are added if a plurality of new candidates are tobe added. It should be noted that the new candidates may include acandidate which is the same as any of the one or more first candidatesand the one or more second candidates, as a result.

It should be noted that a possible method of assigning the secondcandidate is (1) to assign the second candidate to a null candidateafter adding a new candidate or (2) to insert the second candidate intoall the elements of the motion vector predictor candidate lists, therebyinitializing the lists.

First is a description of the case (1) in which the second candidate isassigned to a null candidate after adding a new candidate, in the movingpicture coding apparatus 100 and the moving picture decoding apparatus300.

Here, FIG. 15B shows tables illustrating examples of a motion vectorpredictor candidate list for the prediction direction 0. FIG. 16B showstables illustrating examples of a motion vector predictor candidate listfor the prediction direction 1.

FIGS. 15B and 16B show the motion vector predictor candidate lists inthe case where the second candidate is assigned to a null candidateafter adding a new candidate, and illustrate the case where the maximumvalue M of the number of motion vector predictor candidates is 5 (N=0 to4).

FIG. 17B is a flowchart showing a procedure of calculating a motionvector predictor candidate in the case where the second candidate isassigned to a null candidate after adding a new candidate. It should benoted that the same signs are used for the same processing as those inFIG. 17A. The calculation procedure corresponds to step S102 in FIG. 14executed by the moving picture coding apparatus 100, and alsocorresponds to processing of step S304 in FIG. 22 executed by the movingpicture decoding apparatus 300. The motion vector predictor candidatelist size is fixed to the maximum value M, and thus does not need to becalculated.

In step S151, the motion vector predictor candidate calculation unit 114of the moving picture coding apparatus 100 determines, using the methoddescribed above, whether a prediction block candidate [N] is anavailable predictor candidate.

In step S112, the motion vector predictor candidate calculation unit 114derives a motion vector predictor candidate in the prediction directionX from the prediction block candidate [N] using Expressions 1 and 2above, and adds the derived candidate to a corresponding one of themotion vector predictor candidate lists.

In step S113, the motion vector predictor candidate calculation unit 114searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists.

In step S114, the motion vector predictor candidate calculation unit 114adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists. Here, FIG. 19B is a flowchart showing aprocedure of adding a new candidate in the case where the motion vectorpredictor candidate list size is fixed. FIG. 19B is different from FIG.19A only in the determination method in step S131, and new candidatescan be added until the number of candidates reaches the motion vectorpredictor candidate list size, rather than the number of availablepredictor candidates.

In step S155, the motion vector predictor candidate calculation unit 114adds the second candidate to the end of the motion vector predictorcandidate lists, as shown in (b) in FIG. 15B and (b) in FIG. 16B. Anexample of the second candidate is a motion vector predictor candidatehaving a motion vector whose magnitude is (0, 0).

Here, FIG. 27 is a flowchart showing a procedure of assigning the secondcandidate to a null candidate.

In step S171, the motion vector predictor candidate calculation unit 114determines whether the motion vector predictor candidate list size (forexample, maximum value M−the number of motion vector predictorcandidates) is zero or more. Specifically, it is determined whether themotion vector predictor candidate lists include a null element.

If the determination result of step S171 is true (Yes in step S171), themotion vector predictor candidate calculation unit 114 adds, in stepS172, the second candidate to the null element of a corresponding one ofthe motion vector predictor candidate lists. Furthermore, in step S173,the motion vector predictor candidate calculation unit 114 adds 1 to thenumber of motion vector predictor candidates.

If the determination result of step S171 is false (No in step S171), themotion vector predictor candidate calculation unit 114 ends the additionof the second candidate. At this time, the motion vector predictorcandidate lists will be in the state shown by (b) in FIG. 15B and (b) inFIG. 16B.

It should be noted that here, a description is given assuming that theprocessing is performed by the motion vector predictor candidatecalculation unit 114 of the moving picture coding apparatus 100, it ispossible to successfully decode motion vector predictor indices byperforming the same processing also in the case where the motion vectorpredictor candidate calculation unit 311 of the moving picture decodingapparatus 300 performs calculation to obtain the motion vector predictorcandidate lists.

Next is a description of the case where the moving picture codingapparatus 100 and the moving picture decoding apparatus 300 (2)initialize the motion vector predictor candidate lists by inserting thesecond candidate into all the elements.

Here, FIG. 15C shows tables illustrating examples of a motion vectorpredictor candidate list for the prediction direction 0. FIG. 16C showstables illustrating examples of a motion vector predictor, candidatelist for the prediction direction 1.

FIGS. 15C and 16C show the motion vector predictor candidate lists ineach process when the motion vector predictor candidate lists areinitialized by using the second candidate. FIGS. 15C and 16C eachillustrate the case where the maximum value M of the number of motionvector predictor candidates is 5 (N=0 to 4).

FIG. 17C is a flowchart showing the procedure of calculating a motionvector predictor candidate in the case of initializing the motion vectorpredictor candidate lists by using the second candidate. The calculationprocedure is the processing corresponding to that of step S102 in FIG.14 executed by the moving picture coding apparatus 100, and alsocorresponds to processing of step S304 in FIG. 22 executed by the movingpicture decoding apparatus 300. The motion vector predictor candidatelist size is fixed to the maximum value M, and thus it is not necessaryto calculate the size. It should be noted that N1 in FIG. 17C denotes avalue showing an adjacent block.

In step S161, the motion vector predictor candidate calculation unit 114of the moving picture coding apparatus 100 sets the second candidate asall the motion vector predictor candidates [N1] (N1=0 to 4). An exampleof the second candidate is a motion vector predictor candidate having amotion vector whose magnitude is (0, 0).

In step S162, the motion vector predictor candidate calculation unit 114determines whether the motion vector predictor candidate obtained fromadjacent block N1 is a non-available predictor candidate or a redundantcandidate.

If the determination result of step S162 is true (Yes in step S162), thedetermination in step S162 is made for the next adjacent block N1. Ifthe determination result of step S162 is false (No in step S162), instep S163, the motion vector predictor candidate calculation unit 114obtains the motion vector predictor candidate from the adjacent blockN1, and updates a corresponding one of the motion vector predictorcandidate lists. At this time, the motion vector predictor candidatecalculation unit 114 assigns, to the adjacent block N1, a motion vectorpredictor index having the smallest value among the motion vectorpredictor indices assigned to the second candidate. Then, the motionvector predictor candidate calculation unit 114 overwrites the motionvector predictor candidate having the assigned motion vector predictorindex with the motion vector predictor candidate from the adjacent blockN1.

In step S164, the motion vector predictor candidate calculation unit 114adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists. Here, the motion vector predictor candidatecalculation unit 114 adds a new candidate using the method shown in FIG.19B.

At this time, the motion vector predictor candidate lists will be in thestate shown by (c) in FIG. 15C and (c) in FIG. 16C.

It should be noted that here, a description is given assuming thatprocessing is performed by the motion vector predictor candidatecalculation unit 114 of the moving picture coding apparatus 100, it ispossible to successfully decode motion vector predictor indices byperforming the same processing also in the case where the motion vectorpredictor candidate calculation unit 311 of the moving picture decodingapparatus 300 performs calculation to obtain the motion vector predictorcandidate lists.

Here, the motion vector predictor candidate list shown by (c) in FIG.15B and the motion vector predictor candidate list shown by (b) in FIG.15C are the same, and the motion vector predictor candidate list shownby (b) in FIG. 16B and the motion vector predictor candidate list shownby (c) in FIG. 16C are the same. Thus, it can be seen that the samemotion vector predictor candidate lists can be obtained by using eitherone of (1) the method of assigning the second candidate to a nullcandidate after adding a new candidate and (2) the method of insertingthe second candidate into all the elements of the motion vectorpredictor candidate lists to initialize the lists.

It should be noted that although the present modification shows anexample in which the motion vector predictor candidate having a motionvector (0, 0) is assigned as the second candidate, the presentdisclosure is not limited to this. For example, a motion vectorpredictor candidate assigned to another motion vector predictor indexmay be copied. Furthermore, a candidate may be generated from motionvector predictor candidates assigned to other motion vector predictorindexes, by averaging the magnitude of motion vectors of motion vectorpredictor candidates assigned to other motion vector predictor indices,for instance.

It should be noted that the above modification describes, as a method ofassigning the second candidate, (1) the method of assigning the secondcandidate to a null candidate after adding a new candidate (thirdcandidate) and (2) a method of inserting the second candidate into allthe elements of the motion vector predictor candidate lists toinitialize the lists, the present disclosure is not limited to this.

For example, in step S305 in FIG. 22, the motion vector predictorcandidate calculation unit 311 of the moving picture decoding apparatus300 may add, only in the case where an element indicated by the decodedmotion vector predictor index is a null element, the second candidateonly to that null element, rather than creating motion vector predictorcandidate lists having no null elements. In this case, it is possible toreduce the amount of processing.

In addition, for example, in step S305 in FIG. 22, the motion vectorpredictor candidate calculation unit 311 determines whether the decodedmotion vector predictor index is greater than or equal to the largestvalue of motion vector predictor indices, and if the determinationresult is true, the second candidate may be assigned. Alternatively, forexample, in step S305 in FIG. 22, the motion vector predictor candidatecalculation unit 311 determines whether the decoded motion vectorpredictor index is greater than or equal to the largest value of motionvector predictor indices, and if the determination result is true,clipping processing may be performed on the value of the decoded motionvector predictor index, using the largest value of the motion vectorpredictor indices such that the decoded motion vector predictor indexhas a value smaller than the largest value of the motion vectorpredictor indices.

For example, in the moving picture decoding apparatus 300, if an erroroccurs in deleting a redundant candidate from motion vector predictorcandidates, a state in which a motion vector predictor candidate is notassigned to a decoded motion vector predictor index may occur even if, amotion vector predictor index can be decoded successfully by handling apacket loss which results in a loss of information of a co-locatedblock. Furthermore, for example, the moving picture coding apparatus 100adds, by mistake, a motion vector predictor index having a value greaterthan or equal to the number of motion vector predictor candidates to abitstream, a state may occur in which a motion vector predictorcandidate is not assigned to the decoded motion vector predictor index.

In the above modification, the second candidate is assigned to a nullelement of the motion vector predictor candidate lists, and thus a statecan be avoided in which a motion vector predictor candidate is notassigned to a motion vector predictor index.

Embodiment 3

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 28 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 28, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent disclosure), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 29. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent disclosure). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 30 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present disclosure); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 31 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 32 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 30. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 33A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 33B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent disclosure), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present disclosure),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, various modifications and revisions can be made in any ofthe embodiments in the present disclosure.

Embodiment 4

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 34 illustrates a structure of the multiplexed data. As illustratedin FIG. 34, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 35 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 36 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 36 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 36, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 37 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte. TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 37. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 38 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 39. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 39, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 40, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 41 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present Embodiment 5 an be used inthe devices and systems described above.

Embodiment 5

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 42 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

Embodiment 6

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG-4 AVC, and VC-1 is decoded, theprocessing amount probably increases. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 43illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 42.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 42. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment 4 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 4 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 45. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 44 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG-4 AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 7

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 46A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG-4 AVC. In contrast, a dedicateddecoding processing unit ex901 is probably used for other processingunique to an aspect of the present disclosure. The decoding processingunit for implementing the moving picture decoding method described ineach of embodiments may be shared for the processing to be shared, and adedicated decoding processing unit may be used for processing unique tothat of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 46B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present disclosure, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present disclosure and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentdisclosure and the processing of the conventional standard,respectively, and may be the ones capable of implementing generalprocessing. Furthermore, the configuration of the present embodiment canbe implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present disclosure and the moving picturedecoding method in conformity with the conventional standard.

INDUSTRIAL APPLICABILITY

The moving picture coding method and the moving picture decoding methodaccording to the present disclosure are applicable to any multimediadata, and can improve error resistance in coding and decoding movingpictures. The moving picture coding method and the moving picturedecoding method according to the present disclosure are useful as amoving picture coding method and a moving picture decoding method instorage, transmission, communication, and the like using cellularphones, DVD apparatuses, and personal computers, for example.

What is claimed is:
 1. A method for decoding a current block included ina bitstream, the method comprising: adding, into a candidate list, oneor more candidates of a first type of a motion vector for the currentblock, each of the candidates of the first type being derived from afirst motion vector of a first block that is spatially adjacent to thecurrent block; assigning a respective index to each of the candidates ofthe first type; adding, into the candidate list, one or more candidatesof a second type of the motion vector for the current block, each of thecandidates of the second type being derived from a second motion vectorof a second block that is temporally adjacent to the current block;assigning a respective index to each of the candidates of the secondtype; decoding an index, included in the bitstream, for identifying onecandidate in the candidate list; adding, when the decoded indexindicates one null element among null elements in the candidate list, acandidate of a third type of the motion vector for the current block toonly the one null element indicated by the decoded index among the nullelements in the candidate list, the candidate of the third type beingderived by averaging the candidates of the first type and the candidatesof the second type; predicting the current block using the candidate ofthe third type; and generating an image using the predicted currentblock.
 2. An apparatus for decoding a current block included in abitstream, the apparatus comprising: a processor; and a non-transitorystorage, wherein the processor performs, using the non-transitorystorage, processes including: adding, into a candidate list, one or morecandidates of a first type of a motion vector for the current block,each of the candidates of the first type being derived from a firstmotion vector of a first block that is spatially adjacent to the currentblock; assigning a respective index to each of the candidates of thefirst type; adding, into the candidate list, one or more candidates of asecond type of the motion vector for the current block, each of thecandidates of the second type being derived from a second motion vectorof a second block that is temporally adjacent to the current block;assigning a respective index to each of the candidates of the secondtype; decoding an index, included in the bitstream, for identifying onecandidate in the candidate list; adding, when the decoded indexindicates one null element among null elements in the candidate list, acandidate of a third type of the motion vector for the current block toonly the one null element indicated by the decoded index among the nullelements in the candidate list, the candidate of the third type beingderived by averaging the candidates of the first type and the candidatesof the second type; predicting the current block using the candidate ofthe third type; and generating an image using the predicted currentblock.
 3. A method for decoding a current block included in a bitstream,the method comprising: adding, into a candidate list, one or morecandidates of a first type of a motion vector for the current block,each of the candidates of the first type being derived from a firstmotion vector of a first block that is adjacent to the current block;assigning a respective index to each of the candidates of the firsttype; adding, into the candidate list, one or more candidates of asecond type of the motion vector for the current block, each of thecandidates of the second type being derived from a second motion vectorof a second block that is different from an adjacent block to thecurrent block; assigning a respective index to each of the candidates ofthe second type; decoding an index, included in the bitstream, foridentifying one candidate in the candidate list; adding, when thedecoded index indicates one null element among null elements in thecandidate list, a candidate of a third type of the motion vector to onlythe one null element indicated by the decoded index among the nullelements in the candidate list, the candidate of the third type beingderived by averaging the candidates of the first type and the candidatesof the second type; predicting the current block using the candidate ofthe third type; and generating an image using the predicted currentblock.
 4. An apparatus for decoding a current block included in abitstream, the apparatus comprising: a processor; and a non-transitorystorage, wherein the processor performs, using the non-transitorystorage, processes including: adding, into a candidate list, one or morecandidates of a first type of a motion vector for the current block,each of the candidates of the first type being derived from a firstmotion vector of a first block that is adjacent to the current block;assigning a respective index to each of the candidates of the firsttype; adding, into the candidate list, one or more candidates of asecond type of the motion vector for the current block, each of thecandidates of the second type being derived from a second motion vectorof a second block that is different from an adjacent block to thecurrent block; assigning a respective index to each of the candidates ofthe second type; decoding an index, included in the bitstream, foridentifying one candidate in the candidate list; adding, when thedecoded index indicates one null element among null elements in thecandidate list, a candidate of a third type of the motion vector to onlythe one null element indicated by the decoded index among the nullelements in the candidate list, the candidate of the third type beingderived by averaging the candidates of the first type and the candidatesof the second type; predicting the current block using the candidate ofa third type; and generating an image using the predicted current block.